Influence of Vacancy Defect of Calcium Oxide Surface on the Wettability of Molten Alkali Metal Salt in Calcium Looping Process

Qicheng Chen; Xupan Yang; Yingjin Zhang; Yulong Ding

doi:10.1021/acs.langmuir.0c03566

Influence of Vacancy Defect of Calcium Oxide Surface on the Wettability of Molten Alkali Metal Salt in Calcium Looping Process

Langmuir. 2021 Feb 23;37(7):2503-2513. doi: 10.1021/acs.langmuir.0c03566. Epub 2021 Feb 9.

Authors

Qicheng Chen¹, Xupan Yang¹, Yingjin Zhang², Yulong Ding³

Affiliations

¹ School of Energy and Power Engineering, Northeast Electric Power University, Jilin City, Jilin 132012, China.
² School of Automation Engineering, Northeast Electric Power University, Jilin City, Jilin 132012, China.
³ Birmingham Centre for Energy Storage, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.

PMID: 33560119
DOI: 10.1021/acs.langmuir.0c03566

Abstract

The influence of the vacancy defect of the CaO surface on the wettability of molten alkali metal salt was studied by molecular dynamics simulations. The results indicated that in the temperature range of 800-1100 K, the molten Na₂SO₄ on both VD_calcium and VD_oxygen defect surfaces presented a poor wettability compared to that on the complete surface. Measurement of the density profile and the contact angle of the molten Na₂SO₄ showed that the higher the temperature and defect concentration, the worse the wettability. The micromechanism was revealed by calculating the polarization intensity that the vacancy defect surface led to the formation of the induced dipole moment in the molten Na₂SO₄. Induced polarization caused by defect surfaces reduces the wettability of Na₂SO₄. More importantly, as the temperature and defect concentration increase, various defect surfaces form loose and local weak liquidity structures. These structures are beneficial for the diffusion of carbon dioxide into the solid, but the reduction in the spreading area caused by poor wettability causes the efficiency of the CaL to decline. The vibration difference between Na₂SO₄ and CaO increases with the increased temperature and defect concentration. This means that the thermal energy transportability at the interface is suppressed by poor wettability.